Optimal Treatment for Head Louse Infestation
In Europe control of head louse infestation is now mainly achieved by use of physically acting preparations. The majority of these are based on the polydimethysiloxane, known as dimeticone. This compound exists in a variety of forms from the volatile hexamethyldisiloxane, with a viscosity of just 0.65 centistokes (cSt) through to high molecular weight gums with a viscosity of several million cSt. The level of polymerisation during manufacture results in a range of materials with such variable physical characteristics that selection of the right molecular weight and viscosity is potentially critical for gaining maximum effectiveness in this application.
The first dimeticone based product was Hedrin 4% lotion, approved as a medicine for sale in the UK in 2005, which used dimeticone of 100K cSt viscosity in a decamethylcyclopentasiloxane (cyclomethicone D5) volatile fluid vehicle. This product is also widely used in Europe, mostly as a class I medical device, and has been shown efficacious in several clinical field studies. Since that time variant formulations have been developed in order to improve handling and application of the product and also the cosmetic characteristics.
The original 4% dimeticone lotion is applied for 8 hours or overnight on two occasions a week apart. Subsequent investigations both in the laboratory and in clinical trials have looked at shorter application times for this product and for the variants. One recently described study outcome found that no lice of any development stage were present following the first application of product in a two treatment regimen using a 15 minutes exposure time for a spray gel variant. This report describes the first study investigating the efficacy of a single application regimen for Hedrin 4% dimeticone liquid gel, tested in a comparison trial against two applications of 1% permethrin creme rinse.
Background
In Europe control of head louse infestation is now mainly achieved by use of physically acting preparations. The majority of these are based on the polydimethysiloxane, known as dimeticone. This compound exists in a variety of forms from the volatile hexamethyldisiloxane, with a viscosity of just 0.65 centistokes (cSt) through to high molecular weight gums with a viscosity of several million cSt. The level of polymerisation during manufacture results in a range of materials with such variable physical characteristics that selection of the right molecular weight and viscosity is potentially critical for gaining maximum effectiveness in this application.
The first dimeticone based product was Hedrin 4% lotion, approved as a medicine for sale in the UK in 2005, which used dimeticone of 100K cSt viscosity in a decamethylcyclopentasiloxane (cyclomethicone D5) volatile fluid vehicle. This product is also widely used in Europe, mostly as a class I medical device, and has been shown efficacious in several clinical field studies. Since that time variant formulations have been developed in order to improve handling and application of the product and also the cosmetic characteristics.
The original 4% dimeticone lotion is applied for 8 hours or overnight on two occasions a week apart. Subsequent investigations both in the laboratory and in clinical trials have looked at shorter application times for this product and for the variants. One recently described study outcome found that no lice of any development stage were present following the first application of product in a two treatment regimen using a 15 minutes exposure time for a spray gel variant. This report describes the first study investigating the efficacy of a single application regimen for Hedrin 4% dimeticone liquid gel, tested in a comparison trial against two applications of 1% permethrin creme rinse.